双硫腙修饰有机皂土吸附富集-原子吸收光谱法测定水中痕量镉

Determination of trace cadmium in water by flame atomic absorption spectrometry after preconcentration by modified organobentonite with dithizone

采用静态浸渍法，将双硫腙修饰于用十六烷基三甲基溴化铵（CTMAB）改性的皂土表面，制备了双硫腙修饰有机皂土，对其结构及其对水中镉离子的吸附性能进行了研究，确立了双硫腙修饰有机皂土对镉离子的吸附和洗脱条件，建立了双硫腙修饰有机皂土吸附富集-火焰原子吸收光谱法测定水中镉的新方法。结果表明，经CTMAB改性后，双硫腙可牢固地负载于皂土上，当介质的pH值为4～8时，双硫腙修饰有机皂土对水中镉离子具有很强的吸附能力，其吸附容量可达1．428mg／g。经富集10倍后，该法检出限为0．16μg／L。应用于管网水和河水中镉的测定，加标回收率为92．8％～104．0％，并与石墨炉原子吸收光谱法测定值一致。

Dithizone was modified on the surface of bentonite premodified by cetyltrimethylammonium bromide （CTMAB） by static impregnating to prepare dithizone-modified organobentonite. Its structure and adsorption properties on cadmium in water were studied. The adsorption and elution conditions of dithizone-modified organobentonite on cadmium were defined, and a novel method for the determination trace cadmium in water by flame atomic absorption spectrometry after preconcentration with dithizone modified organobentonite was established. The results showed that dithizone could be firmly loaded on bentonite after modified by CTMAB. When the pH of medium was in the range of 4 -8, dithizone-modified organobentonite has strong adsorption ability on cadmium in water, and the adsorption capacity was up to 1. 428 mg/g. After preconcentrated for ten times, the detection limit was 0.16 μg/L. The method has been applied to the determination of cadmium in tap water and river water, giving the recovery of 92.8%- 104.0%. The results were in good agreement with those obtained by graphite furnace atomic absorption spectrometry（GFAAS）.